Dreamer joined Extreme Championship Wrestling (ECW) in 1993. His first major gimmick in the company had him wrestling in matches in garish green suspenders and acting as something of a "pretty boy".
In 1994, Dreamer was booked in a "Singapore Caning" match against The Sandman – with the loser having to take ten lashes. After losing the match, Dreamer took his lashes, then asked The Sandman for another, causing the crowd to feel sympathy for him as he took the extra lashes. In a later match, Dreamer accidentally blinded The Sandman, first by knocking a lit cigarette into his eye, then hitting in the other with a Singapore cane. Immediately afterwards, Dreamer started aiding The Sandman. He professed that he "didn't mean to do it" and that it was "an accident" as other wrestlers swarmed out to help. The feud continued with Sandman planning to announce his retirement at an ECW show, only to attack Dreamer and reveal he was never actually blind. The feud ended when Tommy Dreamer defeated the Sandman in a no disqualification match.
Though the blind Sandman angle was his first "major" feud in ECW, his later, years-long feud against Raven that started in January 1995 was arguably his most memorable. The two were portrayed as childhood friends who had been competing in different ways their entire lives. Raven's entrance into ECW had him accompanied by Beulah McGillicutty, an overweight girl from their childhood who had a crush on Dreamer and was now a Penthouse Pet. Dreamer and Raven (and Raven's Nest) feuded for two years with Dreamer never getting a win over Raven until Raven's last match in ECW, a Loser Leaves Town match at Wrestlepalooza 1997. During the course of the feud, Beulah had left Raven and was Tommy's valet.
Throughout 1996, during the feud with Raven, Dreamer was also involved in an additional feud with "Prime Time" Brian Lee, who was brought in as Raven's bodyguard. The two had several encounters that ended with Dreamer being chokeslammed through tables. During other fights, the pair brawled outdoors onto the street and into traffic. The feud culminated in a scaffold match at the October 1996 High Incident event, where Dreamer sent Lee off the scaffolding through several tables in the ring below.
After Raven left ECW, Dreamer began a feud with the World Wrestling Federation's Jerry "The King" Lawler. The feud was largely symbolic, with Dreamer representing Extreme Championship Wrestling's "new school" style of wrestling as a concept and Lawler representing the World Wrestling Federation's more "old school" way of doing things.
In 1998, Dreamer had a short feud with The Dudley Boyz (Buh Buh Ray and D-Von), during which they "broke" Beulah's neck. In 1999, on their last night in the company, they cited this incident to get Dreamer to accept a challenge for the ECW Tag Team Championship they had won earlier in the night. He did accept, and won the titles, but was paired with the unexpected partner Raven, who slid into the ring at the last second and made the pin. The team only lasted a short time before it dissolved, with Raven taking the titles and choosing Mike Awesome as his new partner. He also, begrudgingly, became ECW World Heavyweight Champion in 2000 by beating Tazz at CyberSlam, only to lose it to Justin Credible just thirty minutes later.
Dreamer stayed with ECW until it folded in 2001, defeating C.W. Anderson in an "I Quit" match at Guilty as Charged – the final pay-per-view – and teaming with Danny Doring in a win over Julio Dinero and EZ Money in the final ECW show.
After ECW closed its doors, Dreamer signed with the World Wrestling Federation (WWF). He was introduced to WWF audiences on the July 9, 2001 episode of Raw as a member of the WCW/ECW Alliance during the Invasion angle.
He was brought back to the now-renamed World Wrestling Entertainment in March 2002 and placed on the Raw brand. There, he turned face and was given a gimmick that saw him proclaim that he was "just a regular guy", for which he was featured in vignettes and backstage segments showing him in normal situations that were then augmented by "disgusting" antics such as brushing his teeth and his dogs teeth with the same brush and eating food from the floor. However, this angle was short-lived. He soon reverted to his "Innovator of Violence" gimmick in the summer and amassed fourteen reigns as Hardcore Champion. During this time, he was the final person to hold it before it became unified with the Intercontinental Championship in a match with Rob Van Dam at Madison Square Garden. After losing the Hardcore Championship, Dreamer renewed his feud with Raven, defeating him in a Loser Leaves Raw match on June 24 to send him to Raw's sister show, Heat. Dreamer (with a variety of partners) would feud in the fall with Lance Storm and William Regal as he sought revenge for his jaw being broken. Dreamer would make his Royal Rumble debut in 2003, bringing weapons with him and breaking Bill DeMott's hand during the match.
As 2003 and 2004 went on, Dreamer was used less and less on WWE television, and they began allowing him to work as a color commentator on occasion for Heat.
In 2005, Dreamer was a major part of the ECW One Night Stand "reunion show" pay-per-view held under the World Wrestling Entertainment banner. He, along with a number of former ECW stars, took part in promotional hype for the event on episodes of Raw and, with The Sandman, he wrestled the Dudley Boyz in the main event. For the 2006 event, he was placed into an angle that had him and Terry Funk – who had been his "mentor" in the early days of the original ECW – at odds with then-heels, Mick Foley and Edge over the meanings of "extreme". The angle ended with a six-person intergender tag team match at the pay-per-view, where Dreamer, Funk, and Beulah McGillicutty lost to Edge, Foley, and Lita.
When the ECW brand officially launched, Dreamer and the Sandman were put into one of the brands first feuds, an "old school versus new school" feud, against Test and Mike Knox. In November and December, he engaged in a short feud with Daivari and The Great Khali, but Khali was sent to the Raw brand before it could come to a conclusion. Not long after Khali left ECW, The New Breed stable was established, consisting of wrestlers new to ECW: Elijah Burke, Marcus Cor Von, Matt Striker and Kevin Thorn. In response, a stable of ECW Originals was created, and the teams continued to clash in singles and tag matches, trading wins on the weekly ECW show throughout the spring of 2007, while both sides tried to get CM Punk to side with them. The Originals won a standard-rules four-on-four match at WrestleMania 23, which would be Dreamer's first and only match ever on the main card of a WrestleMania. The Originals lost an extreme-rules rematch on the following episode of ECW. The feud continued until a number of roster moves left both sides nearly barren, with it ending at One Night Stand when Dreamer, Sandman and Punk beat Burke, Cor Von and Striker in a tables match.
In late 2007, Dreamer took part in the ECW brand's elimination chase to name a number one contender to the ECW Championship. During the series of matches, also involving Stevie Richards, Elijah Burke, and Kevin Thorn, he added a bandana, worn on his head, to his ring gear. Dreamer emerged victorious in the final match against Burke, only to be surprised by ECW's general manager Armando Estrada forcing him to face Big Daddy V, who promptly beat him for the number one contendership.
In February 2008, Dreamer was paired with ECW brand enhancement talent Colin Delaney as a sort of mentor after Delaney was consistently and easily defeated on the weekly ECW television show. They challenged The Miz and John Morrison for the WWE Tag Team Championship after they defeated them in a non-title match, but they lost the title match in an extreme rules match in March. At WrestleMania XXIV, he participated in a pre-show 24-man battle royal to earn an opportunity for the ECW Championship in the event, a match that was won by Kane. Dreamer qualified for the five-way Singapore cane match at Extreme Rules: One Night Stand to determine a number one contender for the championship; Big Show would win the match.
Following Mark Henry's ECW Championship win at Night of Champions, Dreamer was named his first challenger. At The Great American Bash, Dreamer was defeated by Henry for the championship after Colin Delaney turned on him and cost him the match. On the following ECW, Dreamer defeated Delaney and again on August 12, 2008 in an Extreme Rules grudge match, which would be Delaney's final match in the WWE. Dreamer then turned his attention to Jack Swagger, who made disparaging remarks about Dreamer and ECW. They first faced off in an amateur wrestling match, which Dreamer was disqualified from for using his DDT on Swagger. Then, Swagger defeated Dreamer in an extreme rules match, ending the feud.
On the January 13, 2009 episode of ECW, Dreamer announced that if he failed to win the ECW Championship by June 6, when his WWE contract was to expire, he would no longer wrestle for ECW. The storyline saw Dreamer start a losing streak that ended when he defeated Paul Burchill on the February 24 episode of ECW. On the April 28 episode of ECW, Dreamer received a match for the ECW Championship against then-champion Christian, which went to a no-contest when Jack Swagger interfered. On the May 21 episode of Superstars, Dreamer had another title match with Christian which once again went to a no contest when Swagger interfered, believing he ruined Dreamer's last title chance. Dreamer was granted a one-day extension on his contract, allowing him one last chance at the ECW Championship, challenging the champion Christian and Jack Swagger in a triple threat match at Extreme Rules, where Dreamer pinned Jack Swagger in a hardcore triple threat match, capturing his second ECW Championship almost a decade after he claimed the title in the original ECW, being the only man to hold the belt in the original ECW and in the ECW brand of WWE.
After successfully defending the title against Christian on the June 15 episode of Raw, Dreamer successfully defended the title in a Championship Scramble match at The Bash, before eventually losing the title back to Christian at Night of Champions. On the July 28 episode of ECW, Dreamer announced he would exercise his rematch clause against Christian the following week. The two faced off in an Extreme Rules match, in which Christian retained the championship.
After his championship pursuit had ceased, Dreamer began teaming up with Christian, Yoshi Tatsu and Goldust on various occasions to take on William Regal and his allies Vladimir Kozlov and Ezekiel Jackson, exchanging victories and losses. On the December 29 episode of ECW, Dreamer wrestled Zack Ryder and lost. If Dreamer was to lose the match then he would be forced to retire from in-ring competition. After the match, Dreamer made a farewell speech in which he thanked the fans before exiting the ring with his two daughters. A few days later on January 4, 2010, Dreamer was officially released by WWE.
On the December 17, 2012 episode of Raw, Dreamer made a one-off appearance, teaming with The Miz and Alberto Del Rio in a winning effort against 3MB in six-man tag team match. Later, he was attacked backstage by The Shield.
On the November 30, 2015 episode of Raw, Dreamer returned, teaming with The Dudley Boyz in a six-man tag match against The Wyatt Family, which ended in a no contest. The following week on Raw, Dreamer and The Dudley Boyz would be joined by Rhyno, forming Team Extreme, competing in a 16-man elimination fatal four-way tag team match, where Dreamer would pin Erick Rowan to eliminate The Wyatt Family before Team Extreme would be eliminated by The League of Nations. Later, Dreamer lost to Braun Strowman. At TLC: Tables, Ladders and Chairs, Team Extreme were defeated by The Wyatt Family in an 8-man elimination tag team tables match. The following night on Raw, Team Extreme would challenge The Wyatt Family to a rematch, this time in an 8-man Extreme Rules match, in a losing effort. Dreamer continued to make live event appearances for the WWE in 2016, while becoming a regular guest on the WWE Network exclusive series, The Edge and Christian Show That Totally Reeks of Awesomeness, alongside the show's hosts, Edge and Christian.